A broad based program project on biomedical areas important to human aging is described. Studies will focus on three areas of major gerontologic interest: (1) endocrine and metabolic changes with age, (2) immunologic aging and (3) cellular aging. Endocrine-metabolic projects include cross-sectional human studies in two areas in which important age-related alterations have been documented (a) thyroid hormone economy and (b) physiology of arginine vasopressin - the human antidiuretic hormone. A third endocrine study focusing on age-related alterations in sympathetic nervous system activity and responsiveness will be performed in the rat and can be extended to human investigation. Immunologic aging will be approached in two studies. The cellular component of immune response will be examined in a study of the impact of age on starvation induced changes in human lymphocyte function. Humoral immunity will be the target of a study based at the Hebrew Rehabilitation Center for the Aged on the clinical efficacy of and antibody response to, influenza vaccine across the adult age range and focusing on the elderly. The final project will focus on cellular aging as it examines the influence of age and environmental factors, specifically ultra-violet light exposure, on the in vitro growth characteristics of human epidermis and fibroblasts obtained from skin biopsies of subjects across the adult age spectrum. Care will be taken in the human studies outlined above to screen all subjects to exclude diseases or medications which might influence the variables under investigation and to employ subjects across the entire adult age spectrum.